Merge pull request #193 from carriecwk/DOCSP-45840

(DOCSP-45840) delivery guarantee admonition missing

Author: carriecwk

source/includes/copy-existing-admonition.rst

@@ -2,4 +2,5 @@ If any system changes the data in the database while the source connector
 converts existing data from it, MongoDB may produce duplicate change
 stream events to reflect the latest changes.  Since the change stream
 events on which the data copy relies are idempotent, the copied data is
-eventually consistent.
+eventually consistent, conformant to an "at-least-once" delivery guarantee.
+